Embodiments of the present invention relate generally to therapeutic systems and methods, and more particularly, to techniques that are well suited for the formation of lesions in body tissue.
There are many instances where it is beneficial to perform a therapeutic intervention in a patient, using a system that is inserted within the patient's body. One exemplary therapeutic intervention involves the formation of therapeutic lesions in the patient's heart tissue to treat cardiac conditions such as atrial fibrillation, atrial flutter, and arrhythmia. Therapeutic lesions may also be used to treat conditions in other regions of the body including, but not limited to, the prostate, liver, brain, gall bladder, uterus, and other solid organs. Typically, the lesions are formed by ablating tissue with one or more electrodes. Electromagnetic radio frequency (“RF”) energy applied by the electrode heats and eventually kills or ablates the tissue to form a lesion. During the ablation of soft tissue (e.g. tissue other than blood, bone and connective tissue), tissue coagulation occurs, which leads to tissue death. Thus, references to the ablation of soft tissue are typically references to soft tissue coagulation. “Tissue coagulation” can refer to the process of cross-linking proteins in tissue to cause the tissue to jell. In soft tissue, it is the fluid within the tissue cell membranes that jells to kill the cells, thereby killing the tissue. Depending on the procedure, a variety of different electrophysiology devices may be used to position one or more electrodes at the target location. Electrodes can be connected to power supply lines and, in some instances, the power to the electrodes can be controlled on an electrode-by-electrode basis. Examples of electrophysiology devices include catheters, surgical probes, and clamps.
Currently known surgical probes which can be used to create lesions often include a handle, a relatively short shaft that is from 4 inches to 18 inches in length and either rigid or relatively stiff, and a distal section that is from 1 inch to 10 inches in length and either malleable or somewhat flexible. One or more electrodes are carried by the distal section. Surgical probes are used in epicardial and endocardial procedures, including open heart procedures and minimally invasive procedures where access to the heart is obtained via a thoracotomy, thoracostomy or median sternotomy. Exemplary surgical probes are disclosed in U.S. Pat. No. 6,142,994, the content of which is incorporated herein by reference.
Clamps, which have a pair of opposable clamp members that may be used to hold a bodily structure or a portion thereof, are used in many types of surgical procedures. Lesion-creating electrodes have also been secured to certain types of clamps. Examples of clamps which carry lesion creating electrodes are discussed in U.S. Pat. No. 6,142,994, and U.S. Patent Publication Nos. 2003/0158549, 2004/0059325, and 2004/024175, the contents of which are incorporated herein by reference. Such clamps can be useful when the physician intends to position electrodes on opposite sides of a body structure in a bipolar arrangement.
Although these and other proposed treatment devices and methods may provide real benefits to patients in need thereof, still further advances would be desirable. For example, there continues to be a need for improved ablation systems and methods that can be used by surgeons to treat patient tissue or anatomical features having various sizes, shapes, densities, and the like. Embodiments of the present invention provide solutions that address the problems which may be associated with known techniques, and hence provide answers to at least some of these outstanding needs.